You can either drag and drop the images into the editor window, or use the plus button in the uploads section to search your computer's hard drive for an image.
You should always make sure your images are 'saved for web' using a program like Photoshop or one of the free online image editors.
When you keep your image files as small as possible the editor will load quicker and previewing will be much quicker also.
There are two ‘Autoscaling’ of images options, this will help you fit images to your screens quickly and easily. These options will appear in the widget menu as soon as you click on an image that you have uploaded.
‘Expand to Fit’ allows you to expand a small uploaded image to the width/height of the page you're working on.
‘Display 100%’ will resize an image widget to the original size of the uploaded image file.
You need to have a paid (solo) account in order to upload your own images.